New paleomagnetic results from Neogene to Quaternary volcanic rocks of north of the Lake Van, Eastern Turkey

Abstract

The Eastern Anatolia is an active tectonic region where the collision between the Arabian and Eurasian plates take place. Due to the subduction of Arabian plate’s oceanic lithosphere under Eurasian plate, widespread volcanism observed in large areas began in Serravallian. There is no consensus in the literature for the tectonic evolution of the region. Therefore, there are many geological and geophysical studies conducted with the intention of explaining the tectonic evolution of Eastern Anatolia by geodynamic models. Our paleomagnetism study aims to reveal the tectonic rotations in order to better understand the development of the prevailing tectonism in the region from the volcanic rocks. Paleomagnetic samples were collected from 86 sites of the Late Miocene–Pleistocene volcanic rocks located at the north of Lake Van. Isothermal remanent magnetization studies show that magnetite is the mineral responsible for magnetization in most rocks, while both magnetite and hematite are responsible for the rest of the rocks. Curie temperatures and alteration degrees of rock samples were also determined by high-temperature susceptibility (HTS) studies. In some samples, titanomagnetite component was observed in the heating phase of the HTS measurements. The absence of this component in the cooling step indicates that Ti-magnetite is transformed into magnetite by alteration. The Pleistocene volcanics show counterclockwise rotation of R ± ΔR = 13.4° ± 3.8°. The Pliocene volcanic rocks were defined in four different groups: south of Erciş Fault, north of Erciş Fault, around Muradiye and north of Van. Also, the remarkable clockwise rotation is observed in the north of Van and near Muradiye R ± ΔR = 24.4° ± 17.0° and R ± ΔR = 6.9° ± 9.4°, respectively. In addition, counterclockwise rotation (R ± ΔR = 14.5° ± 6.1°) is obtained in the southern part of the Erciş Fault, while there is no significant rotation (R ± ΔR = 0.6° ± 7.4°) on the northern side. Late Miocene volcanic rocks show no significant rotation either (R ± ΔR = 1.8° ± 13.7°). Our new paleomagnetic results indicate that the left-lateral strike-slip Çakırbey Fault, located to the east of the Erciş fault and extending roughly in the northeast–southwest direction, may be active.